fix #279967 part 1: image resize not correctly honoring aspect ratio

A new member variable `_aspectRatio` of `InspectorImage` is added to remember the image's original ratio. It is also updated when "Lock aspect ratio" is checked. The new two slots help changing the value other than the one changed by user.

mscore/inspector/inspectorImage.cpp

@@ -47,6 +47,12 @@ InspectorImage::InspectorImage(QWidget* parent)
             };
       const std::vector<InspectorPanel> ppList = { { b.title, b.panel } };
 
+      updateAspectRatio(); // initiate aspectRatio
+      connect(b.lockAspectRatio, &QCheckBox::toggled, this, &InspectorImage::lockAspectRatioClicked);
+
+      connect(b.size->xVal, QOverload<qreal>::of(&QDoubleSpinBox::valueChanged), this, &InspectorImage::widthChanged);
+      connect(b.size->yVal, QOverload<qreal>::of(&QDoubleSpinBox::valueChanged), this, &InspectorImage::heightChanged);
+
       mapSignals(iiList, ppList);
       }
 
@@ -56,10 +62,55 @@ InspectorImage::InspectorImage(QWidget* parent)
 
 void InspectorImage::valueChanged(int idx)
       {
-      InspectorBase::valueChanged(idx);
+      InspectorElementBase::valueChanged(idx);
       setElement();     // DEBUG
       }
 
+//---------------------------------------------------------
+//   updateAspectRatio
+//---------------------------------------------------------
+
+void InspectorImage::updateAspectRatio()
+      {
+      Image* image = toImage(inspector->element());
+      qreal widthVal = image->size().width();
+      qreal heightVal = image->size().height();
+
+      _aspectRatio = heightVal != 0.0 ? widthVal / heightVal : 1.0;
+      }
+
+//---------------------------------------------------------
+//   lockAspectRatioClicked
+//---------------------------------------------------------
+
+void InspectorImage::lockAspectRatioClicked(bool checked)
+      {
+      if (checked)
+            updateAspectRatio();
+      }
+
+//---------------------------------------------------------
+//   widthChanged
+//---------------------------------------------------------
+
+void InspectorImage::widthChanged(qreal val)
+      {
+      Image* image = toImage(inspector->element());
+      if (image->lockAspectRatio() && val != 0.0) // to avoid stack overflow
+            b.size->yVal->setValue(val / _aspectRatio);
+      }
+
+//---------------------------------------------------------
+//   heightChanged
+//---------------------------------------------------------
+
+void InspectorImage::heightChanged(qreal val)
+      {
+      Image* image = toImage(inspector->element());
+      if (image->lockAspectRatio() && val != 0.0) // to avoid stack overflow
+            b.size->xVal->setValue(val * _aspectRatio);
+      }
+
 //---------------------------------------------------------
 //   postInit
 //---------------------------------------------------------

mscore/inspector/inspectorImage.h

@@ -27,14 +27,21 @@ class InspectorImage : public InspectorElementBase {
       Q_OBJECT
 
       Ui::InspectorImage b;
+      qreal _aspectRatio; // used for widthChanged/heightChanged
 
       virtual void postInit();
 
    protected slots:
       virtual void valueChanged(int idx) override;
+      void lockAspectRatioClicked(bool checked);
+      void widthChanged(qreal val);
+      void heightChanged(qreal val);
 
    public:
       InspectorImage(QWidget* parent);
+
+   private:
+      void updateAspectRatio();
       };